To define a keyboard shortcut, go to your
data directory and create
(or edit) the file
​Plugins/​User/​Settings/​Key Bindings.json.
For example, if you want to be able to open files with F3, the file would
look as follows:

[
{ "keys": ["F3"], "command": "open" }
]

To apply your changes, open the Command Palette with
Ctrl+Shift+P (or Cmd+Shift+P on Mac) and enter
Reload plugins: